There is a substantial need for machines that are capable of high speed, high quality addressing of discrete media elements, such as envelopes, cards, flats, newspapers, or the like. When media elements are directly printed rather than having address labels applied thereto, they present a much better appearance. The appearance alone may be the difference between a recipient discarding the media without even examining it carefully, or responding to the media element. The quality nature of the print also is important in order minimize postage since the printing of bar codes on media (which must be printed in a high quality manner to be effective) speeds delivery of the media and may significantly reduce postage.
According to the present invention, machinery is provided which is capable of providing high speed, high quality addressing. Utilizing the machine according to the present invention, it is possible to print near letter quality media elements at up to 10,000 per hour, and letter quality elements at up to 6,000 per hour. The media handled can be anything from 3.times.5 inches up to 12 1/4.times.24 inches and up to 1/8 of an inch thick. The print area may be adjusted within a wide range so that it is properly positioned on the media, depending upon the size and composition of the media, and is capable of printing a complete address, including the postal bar code.
The desirable results are achieved according to the invention by utilizing ink jet printers which are positioned above transport belts which move the media therepast at a high speed. The ink jet printers are mounted so that the orifices thereof will not be clogged by rebounding ink particles, yet there is no necessity for a wiper for wiping ink particles off of the print heads. The feeding and transporting system in a machine according to the invention positively feeds each of the individual media elements to and past the print heads in a precisely controlled manner so that the printing is in a uniform position on the media elements, and so that there is no slippage between the media elements and the transport mechanisms that could cause blurring or other non-uniformities in the printing quality.
Media elements are fed from a substrate by first and second feed rollers to a pair of pinch rollers and then onto a plurality of endless transport belts having transport wipers holding the edges of the media elements in positive contact with the transport belts. The first feed roller feeds the media element to the second feed roller, which in turn feeds the media element to the pinch rollers. Once the media element is between the second feed roller and the pinch rollers, operation of the first roller is terminated to ensure no double feeding. A selector bar--the position of which is adjustable with respect to the second feed roller in order to accommodate media of different thickness--is positioned above the second feed roller and has an abrasive strip thereon which will engage the media elements and ensure singulation thereof to the second feed roller. The selector bar may have circumferentially spaced abrasive strips so that when one strip wears out, the selector bar may be rotated so that a new abrasive strip is properly positioned with respect to the second feed roller.
The pinch rollers are biased together by loop springs, and the surface of at least one of the pinch rollers is deformable, and the pinch rollers may move apart--though always biased together by the loop springs--to automatically accommodate media elements of different thickness.
Transport wipers overlay transport belts on opposite sides of the print heads. The transport wipers are mounted by leaf springs or like levers at the leading and trailing ends thereof, the leading edge--with respect to the direction of transport --making an angle less than the angle at the trailing edge, so that the media element may easily enter the area between the transport wiper and the transport belt, but as it moves along the wiper powered by the belt, the wiper will exert a larger force retaining it in place.
The print heads are mounted on movable platforms. Typically, seven print heads would be mounted on one movable platform, while an eighth print head--the print head for printing bar code, or an eighth address line--is mounted on a second platform. The position of the platforms in the horizontal direction perpendicular to the direction of transport of the media elements may be adjusted, as may the vertical spacing between the print heads mounted on the platforms and the media elements moving therepast. The vertical spacing is changed by rotation of eccentric shafts within outer tubes, with the selector bar and the mounting tubes for the print heads being positively tied together so that adjustment of the vertical spacing of one automatically adjusts the vertical spacing of the others by the same amount. The second platform may also be moved in the horizontal direction perpendicular to the direction of transport to position the eighth print head either in an operative printing location, for printing an eighth line of address, or in a location for printing bar code.
Typically, the print heads are jet printers, and in order to prevent rebounding ink from clogging the orifices thereof--yet without requiring a wiper for wiping the ink from the orifices--the print heads are mounted at a small angle--e.g., about 3.degree. --with respect to the vertical (i.e., they make an angle of about 87.degree. with respect to the direction of transport).
Once the media elements have moved past the print heads, and are about to be discharged into a discharge bin or tray, an exit roller is provided which holds the media elements generally horizontally until they have been almost completely discharged, so that the leading edge thereof will not engage a previously-printed media element and drag across it, smearing the printed address information thereon.
It is the primary object of the present invention to provide for the high-speed, high-quality addressing of media elements. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.